Table 2.

HGT events detected in the microbial genomes of each body site.

Body sites	# Genomes	# total genera	# total phyla	a	b	c	d	e
Airways	49	16	4	34	3708	3742	98559	26.34
Blood	45	8	3	6	465	471	50360	106.92
GI tract	452	99	7	16301	139668	155969	219505	1.41
Oral	244	64	8	1080	37201	38281	216387	5.65
Skin	123	16	4	38	2843	2881	91880	31.89
UG tract	146	41	7	206	5366	5572	157006	28.18

a, number of intra-niche gene transfers detected in unique gene sets,

b, number of intra-niche gene transfers detected in mixed gene sets,

c, sum of a and b,

d, number of inter-niche gene transfers detected in mixed gene sets,

e, ratio (d/c).